Ladders having collapsible and expandable ladder sections are used in order to make the ladder smaller for storage and transport purposes.
In the European patent EP-B1-0 527 766 a collapsible ladder is described comprising ladder bars divided into sections interconnected by rungs. In each ladder section is provided retaining or locking mechanisms, designed to automatically release the upper ladder sections, when a rung reaches a lower rung. This means, that subsequent to the release of the lowermost ladder section, the following ladder sections are automatically released, whereby the ladder collapses.
In the European patent EP-B1-1 402 143 another collapsible ladder is described comprising a retaining or locking mechanism on each ladder section. The locking mechanism is provided at both sides of a ladder section and is designed to be manually and individually released at both sides of a ladder section to collapse a ladder section. The locking mechanism on every ladder section needs to be released to completely collapse the ladder. For the locking mechanisms of this ladder, each locking pin has a length, which is sufficient for extending though the locking hole of the ladder section positioned there above and into the hollow space inside the ladder bar, and the ladder bar has an extension below the locking hole, so that when an upper ladder section is released and inserted into an intermediate ladder section, which is locked in relation to a lower ladder section by the locking pin of the lower ladder section, the upper ladder section is stopped from being fully inserted in the intermediate section by a distance in the range of 5-15 cm, by engagement of the extension of the lower ends of the ladder bars of the upper ladder section with the locking pins of the lower ladder section extending through the locking holes into the hollow space of the ladder bars of the intermediate ladder section.
It is to be noticed that when releasing an upper or intermediate ladder section of the ladder described in EP-B1-1 402 143, such a released ladder section will not be fully collapsed before the ladder section below the released ladder section is also released.
Thus, there is a need for a collapsible ladder, which allows the locking pins to extend through the locking holes of the ladder bars, to thereby ensure that the ladder bars are securely held in the extended position, while at the same time, an upper or intermediate ladder section can be fully collapsed, when bringing the locking pins of only the first lower ladder section into the non-locked position. It is an object of the present invention to provide such a telescopically collapsible ladder.